Cataract is a disease of the eye which occurs in the lens in the eyeball and the lens turbidity is collectively called cataract. Aging, heredity, metabolic abnormality, trauma, radiation, poisoning and local malnutrition can cause damage to the lens capsule resulting in increase of permeability and lose of barrier function, or cause metabolic disorders of the lens resulting in denaturation of lens protein and formation of turbidity. If the lens of the eyeball changes from transparence to opacity and has an impact on the sunlight received by eyes, it will affect the eyesight of the eyes. When the degree of turbidity of eyeball is light, the effect on vision is lighter, but as the degree of turbidity gradually deepens, the visual acuity will increase, and severe cases will lead to blindness. Cataract is one of the most common eye diseases leading to blindness and it is a major cause of blindness. Since the mechanism of cataract formation is still unclear, no breakthrough has been made in drug therapy. Therefore, currently the only effective treatment is surgical treatment.
Although the continuous improvement of cataract surgery has provided great assistance to the treatment of cataract, the cure rate of surgical treatment is still far below the incidence rate, and there is the possibility of serious complications. On the other hand, the cost of surgical treatment of cataract is very high, and even in developed countries, cataract imposes a huge burden on the medical insurance system. Therefore, the prevention and treatment with usage of drugs play a decisive role. At present, therapeutic drugs available clinically for cataract include: 1, aldose reductase inhibitors, such as cataline (catalin, kary uni, prifenoxinesodium), phacolysin, bendazac L-lysine, etc.; 2, anti-oxidative damage drugs, such as glutathione, taurine, aspirin, etc.; 3, nutrient metabolism drugs, such as vitamins, carotenoids, etc.; 4, chinese herbal compound including Shihu Yeguang Pill, Qiju Dihuang Pill, Shijueming San and so on. It has been confirmed by long-term clinical trials that these drugs for the treatment of cataract can only delay the deterioration of cataract, but can not reverse the condition to treat cataract. Meanwhile, as China begins to enter an aging society, the number of cataract patients is increasing, and the demand for cataract drugs will become more urgent. Therefore, new varieties of ophthalmic external anti-cataract drugs with safety, good curative effect, strong intraocular penetration and stable nature are needed clinically.
Lanosterol is an amphiphilic molecule enriched in the lens which is synthesized from lanosterol synthase (LSS) through a key cyclization reaction of the cholesterol synthesis pathway and can reduce the abnormal aggregation of lens proteins and make it regularly rearranged to restore crystal transparency. Studies have shown that lanosterol synthase can be detected in the lens. Furthermore, in the Shumiya cataract rat study, a specific combination of homozygous mutations of lanosterol synthase and farnesyl diphosphate farnesyltransferase 1 (FDFT1) can alleviate cholesterol levels in the lens and cause cataracts. Meanwhile, our recent studies have found that lanosterol can significantly reduce pre-formed lens protein aggregates in vitro at the cellular level. It has also been confirmed that lanosterol can reverse the condition of cataract and bring about clarification and transparency of the lens in vivo. This result has recently been published in Nature and attracted worldwide attention and it is a new molecule for the prevention and treatment of cataract.

Kary uni eye drops is a medicine produced by Santen Pharmaceutical Co., Ltd in Japan for the treatment of early senile cataract and the structural formula of its active ingredient is showed below:
